The invention concerns a method for increasing the spontaneity of an electrohydraulically controlled automatic transmission in which a gear shift is carried out by a second clutch closing while a first clutch opens.
In automatic transmissions, the gear shifts can be carried out with overlapping gears, i.e. a first clutch opens and a second clutch closes. The state and pressure curve of the clutches involved in the gear shift is here determined by an electronic transmission control via electromagnetic actuators. Such a method of control or regulations is known from DE-OS 42 40 621.
In automatic transmissions, gear shifts are usually made when a desired performance presettable by a driver, e.g. an accelerator pedal value, exceeds a shift characteristic line of a characteristic field. Besides said gear shifts triggered by means of accelerator pedal, a driver also has the possibility at any moment manually to make downshifts. DE-OS 43 11 886, e.g. thus shows a device by which a driver can make gear shifts by means of a selector lever having a manual gate or switching levers on the steering wheel. In the practice, the following problem can arise when during an overtaking maneuver the driver must let pass the traffic coming in opposite direction. He will then release the accelerator pedal. If the accelerator pedal value exceeds an upshift characteristic line, as consequence of this the automatic transmission carries out an upshift. If during the upshift the driver detects that the opposite road is now free, he will again actuate the accelerator pedal. But the automatic transmission will first terminate the upshift, then follows a blocking time and only then will the automatic transmission carry out a downshift. The problem thus consists in that between the driver's required performance and the reaction thereto of the automatic transmission a corresponding long time elapses. Many drivers find this long reaction time disturbing.
To this extent, the problem to be solved by the invention is to increase the spontaneity of an automatic transmission.